FYI, someone's recently created
which embeds R into Apache 2.0. No design docs that I could find, but
the readme implies that it only works with the
Apache MPM, which makes sense as R isn't yet thread-safe.
At first glance, the functionality mod_R offers seems to be extremely
limited, so limited I'm not even sure why its creator even wants to
use it; but then I don't know much about Apache.